Gas-lift pump



W4 J. CRITES GAS-LIFT PUMP Jan. 3, 1939.

Filed June 1, 1956 INVENTOR.

WILBUR J. CRITES BY \kuam hm mm%m A TTORNEYS.

Patented Jan.3, 1939,

.PATEN'I OFFICE 2,142,413: Gas-1.1m rmur Wilbur J. Orites, Okla, my to Phillips Petroleum Oompany a corporation of ware Applic tion" June 1, 1930, Serial No. 82,974

This invention relates broadly to maintaining reservoir volume or bottom hole pressure in wells. More particularly, the invention relates to methods and devices for returning gas to producraising liquid from well ing formations while holes. Y

In wells such as oil wells, the rate of flow from the producing formations is dependent, v among other things, upon the so-called bottom hole pressure which in turn is dependent, in any given formation; upon the amount of gas present in the producing reservoir available for forcing. the oil or other liquid therein through the pores or interstices of the formation into the wellhole, as will be well understood by one skilled in the art.

In some wells, the bottom hole pressure is suflicient to force the liquid produced to the surface without the aid ,of extraneous measures such as gas-lift, pumps, and the like, until the bottom hole pressure is reduced to such a point that the fluid column in. the well balances the bottom hole pressure, in which case natural flow will cease, or so nearly balances this pressure that therate of flow is no longer economically sufficient. In other wells, the bottom hole pressure is never sufllclent to produce the well without resort to extraneous measures. l 7

As wells flow under these bottom hole pressures, a great deal of the gas within the formation reservoir is exhausted to the surface either in solution with the liquid or in the form of globules in the liquid column. In either case, the amount of gas contained in the reservoir and useful for raising the oil or other liquid is lessened with a-consequent reduction in bottom hole pressure. Flu'thermore, as liquid is removed from the formation reservoir, the gas in the reservoir may expand into the space vacated by the liquid thus further lowering the. bottom hole pressure. 4

After bottom hole pressures are so reduced that V the well will no longer produce asa flowing well,

resort must be had to some additional means to raise the liquid from the well hole. In some instances it is economically desirable to employ the gas-lift method of flowing the well in which gas under pressure is introduced through a conduitfromthewell surfacetoliquid columnto' aerate or lighten the same, thus enabling the lowered bottom hole pressures to flow the well. Either in place of the gas-lift, or after the gas-.

lift is no longer effective, some type of pumping device must be employed for further production. Electrically driven centrifugal pumps. as-lift pumps and the so-caliedsucker rod pumps are .tion, of an embodiment of applicant's invention 11 Claims 401. 103-234) among those used depending upon the conditions encountered in the particular well or field or the rate of. production possible from the well.-

*In any case, it has been found desirable in many'fields to retain as much gas in theppi'oducin'g formation as possible thereby to maintain the bottom hole pressure or reservoir volume thus favoring the ultimate recovery from the formation-of a greater quantity of oil or other liquid. It, therefore, has become thepractice in some pools, notably the Van Tests,- to introduce gas into the formation as the oil or' othe'r'liquid is removed, thereby to repressure the same, maintain bottom hole pressure and reservoir volume; By this practice in combination with controlled flow, it has been found in many instances that a greater ultimate recovery is possible and orderly encroachment of. water is assured, as is well understood by those skilled in the art.

There are, however, many fields which are now on their way to depletion which have not been produced in conformity withthis principle and in which it is desirable, to return-gas to the formation either to increase the bottom hole pressure or to maintain those'already existing. In general, it is believed to be desirable to increase the, amount of gas returned to the formation or reservoir as the depletion progresses.

The primary object of the present invention is to return gas to theproducing formation or reser voir.

An additional object of the invention'is provision of a. device which will accomplish the servation of reservoir gas volumes, the producspecification, claims and the drawing in which:

Figure 1 is a. longitudinal view, partlyin secinplaceinawell. w a

Figure 2 is a detailed enlarged sectional view of the pump element and valve mechanism.

Referring particularly to Figure 1, a well hole is indicated at I. the bottom portion ll of which is adapted to receive oil or other liquid forced from the producing formation Ii. The usual casing i2 extends within the well hole and' is generally cemented in place at the edge of the producing strata as indicated at |3 as will be understood by those skilled in the well drilling ameter than the tubing I4 is attached thereto at the lower end thereof to form a chamber l3 in which is mounted a partition l3 dividing the chamber i3 into two parts, the lower of which serves as a liquid accumulation chamber as indicated at i3. A packer 2 forms a seal between the casing l2 and tubing |l to seal ofl the bottom portion of the well hole. The tubing string I4 is oflset adjacent the lower end thereof as at 22 and extends through the partition I 3 and into the chamber II to a point near the bottom thereof, and carries at its lower end a standing valve 23 in a valve cage 24 which acts as a check valve to prevent the return oi fluid from the eductor tubing l4 to the chamber I3.

Referring to the pumping. element 21 in de-' tall, as shown in Figure 2, a housing indicated at 23 is secured in an aperture in the partition l3 as by wells 33 or anyv other conventional means. The casing .23 may be constructed in two parts, an upper portion 3| and a lower portion '32. The upper portion 3| is provided with a chamber 33 in which is mounted a bellows 33 exposed to the high pressure-gas in the upper portion 01' the chamber ill by means 01' the port 34. Depending from the bellows 35 and fixed thereto is a valve stem 36 having mounted thereon, to move therewith, valve heads 31 and 38 adapted to seat on valve seats 33 and 43, respectively, formed inv the upper portion 3| oi the housing 23. The valve head 31 may be fixedly or adjustably secured to the stem 36 in any well known manner while the valve head 38 is Preferably secured to the stem as by a nut 4i mounted on the stem as by screwthreads 42. The lower portion 32 9f the housing 23 is connected to the upper portion 3| as by screwthreads 43, and serves as a spring guide and housing for a compression spring 44 which surrounds the stem 36 and is-mounted between a flange 45 in the lower housing portion 32, and a plate 46 mounted on the stem 33 as by a screw nut 41. The'spring The tubing ll likewise is provided with a standing valve 25 in I 44 actsas in opposition to the bellows ll'normally to maintain the valve head 31' seated on its seat 33, and may have its'tension varied by the nut 41 thereby to vary the force required to operate the bellows 33. I

Bores 43 and 43' extend partially through the partition |3 in a radial direction and communicate with a port 33 formed in the tubing I4 and a port 43 formed in the tubing ii. A relietpassage ii is formed in a side wall of the upper portion 3| otthe housing 23 and places the low pressure side of the bellows 35 in communication with the bore 43' and thence to the exterior of the tubing I! through the port 43 to relieve any back pressure which would tend to build up behind'the bellows 33 in operation. A bore or passage ii is formed in the housing'part 3| and communicates with the passage 43' and a port 52 formed in the valve seat 43; With the valve heads in the positions shown, it will [be apparent that any gas in the chamber l3 may flow through the port 52, passage passage 43' and port 43 to the exterior of the tubing II. A second chamber 53 is formed in the upper portion 3| of the housing 23, in which is mounted a bellows 54 having one side exposed to the pressure existing in the bellows chamber 33 through the medium of the port 55 and the other side exposed to the pressure existing in the chamber I3 through the medium of the port 56. A plug 51 may be screwed into one end of the chamber 53 and is provided with a passage 58 extending from the chamber 53 to a passage 59 in the housing portion 3| which in turn communicates with the eduction tubing |4 through the passage 43 and port 53 A needle valve 63 is secured to one side of the bellows 54 and serves to open and closethe bore 58 in response to pressure diflerentials existing at one side or the other of the bellows. Gas under pressure may pass from the bellows chamber 33 into' the spring housing 32 when the valve head 31 is open and the valve head 33 in closed position, through the ports 3| in the valve head 38 and the ports 62 in the spring follower plate 43. Ports or openings 33 in the spring housing 32 provide for gas passage therefrom into the liquid accumulation chamber i3.

The'pumping device is assembled on the tubing string I4 at the well surface. It is to be understood that the partition l9 together with the pumping element 21 is first welded or otherwise secured in place in the tubing I! which is then slipped over the tubing string l4 and the upper end may be peened over into engagement with the tubing string and welded or otherwise secured thereto. The tubing string I4 together with the pumping device is then lowered within the well hole in the usual manner until the packer 2| seats against a shoulderinot shown) on the casing i2. The casing head is then sealed in any of the known ways as will be well understood by those skilled in the art. At this point, the

-lower end of the tubing l1 including the pumping element 21 will be submerged in the well fluid which will stand in the well hole at various heights depending upon the bottom hole pressure and available liquid.

In operation, the liquid standing in the well.

partial filling; the chamber ll escapes therefrom the ports 08,12, It, passage ll" and'port to the, exterior of the tubing II. Gas-under pressure is'thenadmitted through the pipe ll to'the casing 12 from whence it passes the ports 2| into the chamber ll through the port I to the bellows chamber ll where it exerts suiiicient pressure upon the bellows SI to compress "the same, thus opening the valve 8] and closing, the, valve 88. It can now pass through theports ll, spring ports I and ports pressures meme inherent spring of the bellows i4 maintains theneedle valve '0 in closed p sition. when the liquid accumulation chamber has been exhausted of liquid the pressure of the admitted as i sreduced, generally by an intermitting valve at-the well surface which shuts. all the supply of gas at predetermined intervals, 3

or any other-form, of'control may be used, sufficiently to enable the spring 44 tov close the valve Il'and open the valve 38.; It is to be understood that the pressure diflerentialnecessary to opcrate the valve maybe relatively small depending upon the setting-oi the spring tension. For

instance, in some wells it may be necessary or desirable to use a gas pressure of around threeor four hundred pounds per square 'inchto raise the liquid in which case the valve might be set to operateat a fifty-pound per square inch differential. As the valve 31 closes, the gas under pressure in'the chamber II is cut ofl' from the accumulation chamber ll and'the compressed gas within this chamber may escape through the ports 03, ii, 52 passages, i and 48' and port 49 to the exterior'o'fthe'tubing H. Y At this instant, pressure on the side of the bellows exposed to the liquid accumulation chamber through the port 5 of the bellows 54, is reduced to a rela-' tively low value whereas the pressure on the other side in communication with the bellows 'cham ber 33 through the port 55 is maintained at a a relatively high value, ,thus compressing the bel-,

lows 54, unseating the valve 60 and permitting gas under pressure to pass through the port 55, chamber 53 passages 58, 59 and 48 and port 5!! to the eduction tubing H where it serves to aerate the column and to provide a compressible medium toaid in controlling the pressure in the accumulation chamber-ll in accordance with the setting of the choke .II. As the gas is exhausted from the liquid accumulation chamber, liquid from the well again enters the chamber through the standing-valve to 1111 the same. The fluid in the eduction pipe is prevented from returning to the chamber by the standing valve 23. The intermitter or other control at the well surface then" raises the gas pressure in the upper portion of the chamber l8 sufllcientlyto again open the valve 31 to repeat'the cycle. It will then be apparent that after the eduction tubing has filled each slug of liquid passing thereuntoforces a slug outat thetop and'the introduction of gas into the tubing during thegas exhaust oi the chamber ll serves to maintain the liquid in the eduction tube in a state of constant motion. I

.It will be observed that the packer 2| forms a sealed space between the tubing I1 and the well hole adjacent the producing formation.

a I claim as my invention:

' of the reservoir, prjas it maybe expressed, mainance of reservoir volume. a I It is generallydesirable to so locate the port I! that the gas will be returned to that'portion of the formation nearest to the spacewhich it normally occupies in the,producingreservoir. While'that aspectcf the invention concerned with returning of gas to the formation is applie ticularly effective in those formations in which the producing sand is thick and in sections.

Q-cable to'formations of most any type, it is par-,

f-"It is to be understood that the embodiment of applicant's invention illustrated in the drawing and described above isfor the purpose of illustration only, and that changes in structure and design are contemplated within the scope of the subjoined claims;

1. In a device for raising liquids and for returning gas to a producing formation, a chamber forv the accumulation of liquid located adjacent the producing formation, means to seal thechamber in the well bottom to form a closed space surrounding the chamber, a conduit for conducting gas under pressure to said chamber, a conduit for the educti on of: liquid from said chamber, and means for exhausting the gas within the chamber to the closed space and to the formation.

- 2. Ina gas-liftpumping devicepa chamber. in

the well hole adjacent the producing formation,

valve means within said chamber for the admission of liquid from said well to said chamber, means to form a sealed space between thejchamher and the producing formation, means for conducting gas under pressure to said chamber, means for conducting liquid therefrom and means -in communication-with said chamber and said sealed. space to conduct exhaust gas from said chamber to the formation. I r

3. In a device for raising liquids from a well and for re-pressuring; producing formations, a casing extending within the well to'a point adjacent said formation, a tubing within the well hole extending into the producing formation and spaced therefrom to form a chamber for the accumulation of liquid therein, a tubing string extending from the well surface to said chamber for the eduction of liquid therefrom, a source of gas under pressure in communication with said chambena packer between the casing and cham-' her to seal thespace between the chamber and formation; and means to conduct the exhaust gases from said chamber to said sealed space.

4. In a device for raising liquid from a well reservoir, a liquid accumulation chamber within from a well the'reservoir, a packer between the well wall and a said chamber forminga seal therebetween above from said chamber to said reservoir, and means to control the flow of gas through said conduits. 5. In a device for raising liquid from a well reservoir and for returning gas thereto, a liquid accumulation chamber in said reservoir, including a check valve to admit liquid to said chamher. a packer between said chamber and the well wail forming a seal therebetween, a gas Industion conduit in communication with said chamcontrol the flow of gas through said induction and exhaust conduits.

6. In a device for raising liquids from a well and for re-pressuring the producing formation, a chamber within the well and extending into said formation, a check valve for admitting liquid to said chamber, a seal between said chamber and said formation adjacent the upper end of said chamber, means for introducing gas under pressure to said chamber, means for conducting liquid therefrom to the well surface, and means for conducting exhaust gas from said chamber to V i I Y anism mounted in the partition with a tension said formation.

, 7. A device for raising liquids from a well and for returning gas to the producing formation,

conduit in communication with said chamber for the introduction of gas under pressure thereto, a conduit in communication with said chamber for the eduction of liquid therefrom, a conduit for exhausting gas from said chamber to the producing formation, and means to control the flow of liquid through said eduction conduit thereby to control the volume of gas to be exhausted to said-formation.

8. In a device of the character described, a chamber for the accumulation of liquid therein, a conduit for admitting gas under pressure to said chamber, a conduit for the eduction of liquid from said chamber, a passage from said chamber to the exterior thereof for the exhaust of gas therefrom, a conduit for the introduction of gas into said liquid eduction conduit, means to control the admission of gas to said chamber and the exhaust of gas therefrom, and means responsive to pressure differences between the gas admission conduit and said chamber to control the admission of gas to said last named conduit.

9. A gas operated pump structure for raising liquids from a well hole and for returning gas to a producing formation, comprising a pump housing adjacent the producing formation having a partition dividing the housing into upper and 55 lower chambers, a packer between the housing tition having its lower end in communication with the lower chamber, and valve means mounted in the partition directing the gas under pressure into, thelower chamber to force the liquid accumulated therein into the induction tube and an exhaust port in the valve for exhausting the gas in the lower chamber into the formation for repressuring purposes when the source of gas supply is. closed at the surface of the well.

10, A gas operated pump structure forrsising liquid from a well hole and for returning" gas to a producing formation, comprising a pump housing adjacent the producing formation having a partition dividing the housing into an upper gas'chamber and a lower liquid accumulation chamber, a packer between the housing and producing formation to seal the space between the housing and formation, a check valve in the lower chamber, a liquid eduction pipe mounted in the partition having its lower end in communication with the lower chamber and connecting with the well tubing at its upperend, a pilot valve mechspring to keep the valve normally seated, a bellows connected to the valve and subjected to the gas pressure to lift the pilot valve from its seat thus directing the gas pressure into the accumulation chamber to force the oil therein into the eduction pipe and a by-pass for exhausting the accumulation chamber of gas when the gas pressureis closed at the surface of the well and to direct the gas pressure into the gas formation an thus repressure the same.

11. A gas operated pump structure for raising liquid from a well hole and for returning gas to a producing formation, comprising a pump housingadjacent the producing formation having a partition dividing the housing into an upper gaschamber and a lower liquid accumulation chamber; a packer between the housing and producing formation to seal the space between the housing and formation, a liquid eduction pipe mounted in the partition having its lower end in communication with the lower chamber and connecting with the well tubing at its upper end, a pilot valve mechanism mounted in' the partition with a tension spring to keep the valve normally seated, a bellows connected to the valve and subjected to the gas pressure to lift the pilot valve from its seat against the pressure exerted by the tension spring to thus allow the pressure gas to enter the accumulation chamber to force the liquid therefrom, a by-pass to exhaust the accumulation chamber when the gas pressure means is closed and adapted to direct the gas from the accumulation chamber into the iiquid formation to repressure the same and a second by-pass controlled by a bellows adapted to establish communication between the gas pressure and the eduction pipe when the pilot valve is closed to aerate the oil column.

W'ILBUR J. CRITES. 

